A database table may store data in rows and columns. When data is stored in columns, a column of values may be represented as a sequence of value IDs. A search for a value queries the database table and identifies the rows conditioned on the particular value ID. A database processes a query by searching a table and an index that is associated with the table. An index may provide a mapping between one or more value IDs and rows in a database table. Conventionally, a database loads an entire index into the database memory, which results in faster data access and retrieval. However, because the size of the index stored in the database memory is proportional to the size of the underlying value ID sequence, the index may have large memory foot print, which means the memory space in the database memory cannot be used for other database operations.
In the drawings, like reference numbers generally indicate identical or similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.